1 /*

     2  * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package sun.tools.jstat;

    27 

    28 /**

    29  * A class that represents a mathematical expression as a tree structure

    30  * containing operators as interior nodes and operands as leaves. The

    31  * operands can be literals or lazily bound variables.

    32  *

    33  * @author Brian Doherty

    34  * @since 1.5

    35  */

    36 public class Expression {

    37     private static int nextOrdinal;

    38     private boolean debug = Boolean.getBoolean("Expression.debug");

    39     private Expression left;

    40     private Expression right;

    41     private Operator operator;

    42     private int ordinal = nextOrdinal++;

    43 

    44     Expression() {

    45         if (debug) {

    46             System.out.println("Expression " + ordinal + " created");

    47         }

    48     }

    49 

    50     void setLeft(Expression left) {

    51         if (debug) {

    52             System.out.println("Setting left on " + ordinal + " to " + left);

    53         }

    54         this.left = left;

    55     }

    56 

    57     Expression getLeft() {

    58         return left;

    59     }

    60 

    61     void setRight(Expression right) {

    62         if (debug) {

    63             System.out.println("Setting right on " + ordinal + " to " + right);

    64         }

    65         this.right = right;

    66     }

    67 

    68     Expression getRight() {

    69         return right;

    70     }

    71 

    72     void setOperator(Operator o) {

    73         if (debug) {

    74             System.out.println("Setting operator on " + ordinal + " to " + o);

    75         }

    76         this.operator = o;

    77     }

    78 

    79     Operator getOperator() {

    80         return operator;

    81     }

    82 

    83     public String toString() {

    84         StringBuilder b = new StringBuilder();

    85         b.append('(');

    86         if (left != null) {

    87             b.append(left.toString());

    88         }

    89         if (operator != null) {

    90             b.append(operator.toString());

    91             if (right != null) {

    92                 b.append(right.toString());

    93             }

    94         }

    95         b.append(')');

    96         return b.toString();

    97     }

    98 }